In the pharmaceutical sector and also in the dietary supplement sector, numerous preparations are filled into capsules which are intended to be taken orally. In the case of various preparations, it is important that they are prepared as a single dose in the capsule with a fixedly defined and exactly contained mass. Suitable metering devices and methods are intended to ensure that very tight mass tolerances of for example ±2 mg are maintained under the conditions of high-volume filling.
Such requirements placed on the target mass are increasingly also associated with the desire for suitable testing and verification measures. In order to meet such demands, in particular capsule filling machines constructed in a multitrack manner and multitrack weighing systems are in use. The filled capsules are either checked for the correct filling quantity at random or, given a corresponding requirement, fed to a 100% in-process control. To this end, the capsules are conveyed to a multitrack capsule weighing machine. If there is no direct connection, the capsule weighing machine can also be loaded manually. In the capsule weighing machine, a capsule transporter transports the individual capsules up to a weighing unit. Upon reaching the weighing unit, the capsule is stopped from moving via a stopping device and is subsequently deposited on a weighing receptacle of the weighing unit in a manner lying horizontally. Testing weighing of the filled capsule is carried out there before the latter is transported onward and is replaced on the weighing device by the next capsule.
The capsules can be weighed directly in single-track or multitrack capsule filling machines with a weighing device, or in a separate single-track or multitrack weighing machine. This weighing machine can be loaded directly by a capsule filling machine or be filled manually by hand. As a result, as per the above description, 100% in-process control is actually possible. However, it has been found that the weighing carried out in such a way represents the limiting factor as regards throughput speed and output quantity. For weight measurement to be carried out repeatably and exactly in the milligram range, each particular capsule has to rest completely still on the weighing receptacle. The capsule transported up at high speed thus first of all has to be braked, that is, stopped, and then deposited cleanly before the actual weighing operation can be carried out. For rapid onward transport, a high acceleration is then necessary again. In order, nevertheless, to have a sufficiently long rest phase for the measurement, a particular cycle rate of the machine overall must not be exceeded. An increase in the output quantity can only be achieved through an increase in the number of machine tracks under these conditions, this further increasing the investment costs, which are in any case already high, for the weighing device.